The photonic transmission of high frequency microwave signals is typically accomplished by impressing the RF as an envelope on the amplitude of an optical carrier, using either an electro-optic (EO) or electro-absorption (EA) modulator. Although linearized EO modulators have been proposed for many years, the vast majority of modulators available for analog transmission still suffer from intrinsic nonlinearities in their transfer function. For example, the most common Mach Zehnder EO modulator possesses a raised-cosine modulation transfer curve.
As a result, intermodulation products and harmonic distortions are incurred at the transmitter end of these intensity or amplitude modulated analog links, giving rise to well-known impairments of the link's spur free dynamic range (SFDR).
Thus, what is needed is a high spur free dynamic range in an optical link. Further, what is needed is a high spur free dynamic range in an optical link for high frequency signals.